Cooper: 'My Tamara character is dense'

Speaking at the Cannes press conference for the film, Cooper revealed that he wanted to make his egotistical rock star Ben Sergeant sympathetic.

"I didn't want you to hate him so I thought it'd be nice if he was quite sweet and endearing. He's just a little bit stupid, really," he said.

"He doesn't really know who he is or what he's doing and so thinks the world revolves around him. He can't believe it when people don't know the band Swipe have split up."

The Mamma Mia! star added that he was allowed to improvise when his character was asked to serenade Gemma Arterton's eponymous heroine.

"There were moments when he plays the guitar and sings such dreadful love songs to Tamara," he commented. "That we fooled around with and just came up with something, it never felt like it was restricted... He's just a bit dense. Do I feel like him? Absolutely!"

Cooper also admitted that the role fulfilled a personal ambition as he has "always dreamed of being a rock star. Unfortunately I have no musical talent whatsoever but continue to try".